The detection of pathogenic microorganisms in biological fluids should be performed in the shortest possible time, in particular in the case of septicemia for which the mortality remains high in spite of the broad range of antibiotics which are available to doctors. The presence of biologically active agents such as a microorganism in a patient's body fluid, especially blood, is generally determined using blood culture bottles. A small quantity of blood is injected through an enclosing rubber septum into a sterile bottle containing a culture medium, and the bottle is then incubated at 37° C. and monitored for microorganism growth.
Instruments currently exist on the market in the U.S. that detect the growth of a microorganism in a biological sample. One such instrument is the BacT/ALERT® 3D instrument of the present assignee bioMérieux, Inc. The instrument receives a blood culture bottle containing a blood sample, e.g., from a human patient. The instrument incubates the bottle and periodically during incubation an optical detection unit in the incubator analyzes a colorimetric sensor incorporated into the bottle to detect whether microbial growth has occurred within the bottle. The optical detection unit, bottles and sensors are described in the patent literature, see U.S. Pat. Nos. 4,945,060; 5,094,955; 5,162,229; 5,164,796; 5,217,876; 5,795,773; and 5,856,175, the entire content of each of which is incorporated by reference herein. Other prior art of interest relating generally to the detection of microorganisms in a biological sample includes the following patents: U.S. Pat. No. 5,770,394, U.S. Pat. No. 5,518,923; U.S. Pat. No. 5,498,543, U.S. Pat. No. 5,432,061, U.S. Pat. No. 5,371,016, U.S. Pat. No. 5,397,709, U.S. Pat. No. 5,344,417 and its continuation U.S. Pat. No. 5,374,264, U.S. Pat. No. 6,709,857; and U.S. Pat. No. 7,211,430, the entire content of each of which is incorporated by reference herein.
Substantial, and potentially life-saving, clinical benefits for a patient are possible if the time it takes for detection of a microbial agent in a blood sample could be reduced. A system that meets this need has heretofore eluded the art. Accurately identifying the presence of microorganisms in a sample also requires that the correct amount of fluid be in the sample. Too much or too little fluid may alter the growth rate of microorganisms, thus introducing error into the detection process. Foam in a specimen container can, in some cases, interfere with accurate determination of fill level. Thus, it is important to detect the presence of foam in specimen containers prior to determining fill level and detecting the presence of microorganisms.
Many further advantages and benefits over the prior art will be explained below in the following detailed description.